FLS2023 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
MO2L3	Review of Harmonic Cavities in Fourth-generation Storage Rings	storage-ring, synchrotron, electron, survey	8
	F.J. Cullinan, Å. Andersson, P. Tavares MAX IV Laboratory, Lund University, Lund, Sweden
	Several third generation light-source storage rings have used harmonic cavities to lengthen the electron bunches. With the advent of the fourth generation however, they have become an almost universal feature as the small transverse electron beam sizes make long bunches essential for increasing Touschek lifetime and reducing emittance blow-up from intrabeam scattering. Multiple technological solutions exist for the implementation of harmonic cavities and which to use remains an open question for many facilities. This is therefore a very active area of study in which there is strong collaboration within the community. Avoiding coherent collective beam instabilities is of particular concern. In this talk, I will summarise the results obtained so far. I will also give an overview of the observations made at the MAX IV 3 GeV ring, the first fourth generation storage ring which was commissioned with normal-conducting passive harmonic cavities already installed. Finally, I will discuss potential future directions.
	Slides MO2L3 [3.035 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO2L3
About •	Received ※ 24 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 27 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MO3B2	Beam Dynamics Using Superconducting Passive Harmonic Cavities with High Current per Bunch	dipole, synchrotron, impedance, emittance	14
	A. Gamelin, V. Gubaidulin, A. Loulergue, P. Marchand, L.S. Nadolski, R. Nagaoka SOLEIL, Gif-sur-Yvette, France N. Yamamoto KEK, Ibaraki, Japan
	In 4th generation synchrotron light sources, harmonic cavities (HCs) are critical components needed to achieve the required performance. They provide longer bunches, which helps to reduce statistical effects (intra-beam scattering and Touschek effect). In "timing" modes, where the bunch spacing is larger than in conventional modes and the number of particles per bunch is higher, this need is even greater. In this article, we present the beam dynamics in the high current per bunch regime and how it interacts with the single bunch collective effects. In particular, a dipole-quadrupole instability is observed above the microwave threshold and a coupling between the dipole and cavity modes is shown to limit bunch lengthening at low current. The effective gain from the use of HCs in terms of lifetime, emittance, and energy spread is also discussed.
	Slides MO3B2 [1.529 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B2
About •	Received ※ 13 August 2023 — Revised ※ 15 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MO3B3	Bunch-lengthening RF System Using Active Normal-conducting Cavities	kicker, synchrotron, beam-loading, controls	18
	N. Yamamoto, D. Naito, S. Sakanaka, T. Yamaguchi KEK, Ibaraki, Japan A. Gamelin, P. Marchand SOLEIL, Gif-sur-Yvette, France
	Bunch lengthening using a double RF system (fundamental + harmonic cavities) is essential in preserving the extremely low emittance in fourth and future generation synchrotron light rings. Recent studies have revealed that, in many cases, unstable beam motions, as so-called "mode-0" and "periodic transient beam loading" instabilities, prevent from reaching the optimum bunch lengthening condition with low and high beam current, respectively, even in symmetric filling patterns. While reducing the R/Q is beneficial for the latter, it will worsen the former. To achieve an efficient bunch lengthening system, we proposed a promising solution based on a powered TM020-type harmonic cavity with RF feedbacks (RF-FBs), as reported at FLS2018. Based on this concept, we are developing both fundamental and harmonic cavities using the TM020 resonant mode, a kicker cavity having a bandwidth >5MHz, bunch-phase monitor (BPhM) and RF-FBs. In this presentation, we describe our overall bunch lengthening system including cavity and BPhM designs. We also present particle tracking simulation results demonstrating that the bunch lengthening limitations can be alleviated by means of direct RF-FBs*. N. Yamamoto et al., PRAB 21, 012001, 2018. T. Yamaguchi et al., accepted in NIM A. * D. Naito et al, IPAC2021, MOPSB331, 2021. **** N. Yamamoto et al., IPAC23, WEPL161, 2023.
	Slides MO3B3 [2.655 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B3
About •	Received ※ 22 August 2023 — Revised ※ 23 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU1C1	An Efficient Optimisation of a Burst Mode-Operated Fabry-Perot Cavity for Compton Light Sources	laser, electron, photon, optics	46
	V. Mușat, E. Granados, A. Latina CERN, Meyrin, Switzerland E. Cormier CELIA, Talence, France G. Santarelli ILE, Palaiseau Cedex, France
	The burst mode operation of a Fabry-Perot cavity (FPC) allows for the generation of a high-intensity photon beam in inverse Compton scattering (ICS) sources. The geometry and burst mode parameters of the FPC can be optimised to maximise the scattered photon flux. A novel optimisation method is presented, significantly improving processing speed and accuracy. The FPC’s dimensions, mirror requirements, and effective energy can be obtained from the electron beam parameters at the interaction point. A multi-objective optimization algorithm was used to derive the geometrical parameters of the FPC; this brought orders of magnitude increase in computation speed if compared to the nominal Monte Carlo-based approaches. The burst mode parameters of the FPC were obtained by maximizing the effective energy of the laser pulse in the FPC. The impact of optical losses and thermal lensing on the FPC parameters is addressed. Preliminary parameters of an ICS source implementing this novel optimisation are presented. The source could reach high-performance photon beams for high-energy applications.
	Slides TU1C1 [1.776 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C1
About •	Received ※ 22 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU1C2	Evolution of the Inverse Compton Scattering X-ray Source of the ELSA Accelerator	laser, electron, alignment, scattering	50
	A. Pires, R. Rosch, J. Touguet CEA, Arpajon, France N. Delerue Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France V. Le Flanchec CEA/DAM/DIF, Arpajon, France
	The Inverse Compton Scattering (ICS) X-ray source of ELSA accelerator at CEA-DAM, presents an efficient approach for generating X-rays with a compact linac. The source consists of a 30 MeV, 15 ps rms, up to 3 nC electron beam; and a table-top Nd:YAG laser. X-rays are produced in the 10-80 keV range, higher X-ray energies achieved with frequency doubling of the laser. The yield is increased by a factor of 8 thanks to an optical mirror system developed at CEA, folding the laser beam path and accumulating successive laser pulses. We present a new version of the device, with improvement of mechanical constraints management, adjunction of motorized mirrors, and a new imaging system. A Chirped Pulse Amplification (CPA) system was also designed, enabling higher amplification levels without exceeding laser damage threshold. The uniqueness of this CPA system lies in its use of a short wavelength bandwidth, ±250 pm after Self-Phase Modulation (SPM) broadening, and a line density of 1850 lines/mm for the gratings of the compressor. The pulse is stretched with a chirped fiber Bragg grating (CFBG) before amplification in Nd:YAG amplifiers, and compressed by a double pass grating compressor.
	Slides TU1C2 [7.085 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C2
About •	Received ※ 25 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU3D4	Compact HOM-damped RF Cavity for a Next Generation Light Source	HOM, damping, impedance, operation	74
	H. Ego KEK, Ibaraki, Japan T. Asaka, N. Nishimori QST, Sendai, Miyagi, Japan T. Inagaki, H. Tanaka RIKEN SPring-8 Center, Hyogo, Japan T. Ohshima, T. Tomai, H. Yamaguchi JASRI, Hyogo, Japan
	A beam-accelerating RF cavity with a new HOM-damping structure was designed in order to suppress coupled-bunch instabilities in a next generation light source with an ultra-low emittance and supplying X-rays approaching their diffraction limits. The TM020 mode at 509 MHz is selected as a beam-accelerating mode because it has a high Q-value of 60,000 and a shunt impedance sufficient for beam acceleration and brings a compact HOM-damping structure to the cavity differently from massive types of cavities with waveguides or pipes extracting HOM power. Two shallow slots are cut on the cavity inner-wall and materials absorbing RF waves are directly fitted into them. They work as HOM dampers without affecting the RF properties of the beam-accelerating mode. A prototype cavity of OFHC copper was fabricated to demonstrate the HOM-damping and generating an accelerating voltage of 900 kV in the cavity. Since the cavity was successful in operation up to 135 kW, the feasibility of both the high-power operation and the damping structure was proved. Four actual cavities were produced and installed to the new 3-GeV synchrotron radiation facility, NanoTerasu in Japan.
	Slides TU3D4 [8.581 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU3D4
About •	Received ※ 22 August 2023 — Revised ※ 23 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU4P34	Recent Developments of the cSTART Project	storage-ring, injection, electron, lattice	155
	M. Schwarz, A. Bernhard, E. Bründermann, D. El Khechen, B. Härer, A. Malygin, A.-S. Müller, M.J. Nasse, G. Niehues, A.I. Papash, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski, C. Widmann KIT, Karlsruhe, Germany
	The combination of a compact storage ring and a laser-plasma accelerator (LPA) can serve as the basis for future compact light sources. One challenge is the large momentum spread (~ 2%) of the electron beams delivered by the LPA. To overcome this challenge, a very large acceptance compact storage ring (VLA-cSR) was designed as part of the compact STorage ring for Accelerator Research and Technology (cSTART) project. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for the VLA-cSR to benchmark and emulate LPA-like beams. In a second stage, a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and the Helmholtz Institute Jena (HIJ). The small facility footprint, the large-momentum spread bunches with charges from 1 pC to 1 nC and lengths from few fs to few ps pose challenges for the lattice design, RF system and beam diagnostics. This contribution summarizes the latest results on these challenges.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P34
About •	Received ※ 21 August 2023 — Revised ※ 22 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WE4P33	Design of a 166.6 MHz HOM Damped Copper Cavity for the Southern Advanced Photon Source	HOM, impedance, damping, photon	207
	J.Y. Zhu, X. Li, Z.J. Lu IHEP, Beijing, People’s Republic of China J.B. Yu IHEP CSNS, Guangdong Province, People’s Republic of China
	Funding: This work was supported by the National Natural Science Foundation of China (12205168). The Southern Advanced Photon Source (SAPS) aims to achieve ultra-low emittances and is expected to adopt low-frequency cavities (< 200 MHz) to accommodates on-axis injection. This paper focuses on the design of a 166.6 MHz HOM-damped normal conducting (NC) cavity for the SAPS. We propose a novel approach to achieve efficient HOM damping by optimizing the lowest frequency HOM and implementing a beam-line absorber in a coaxial resonant NC cavity. Notably, unlike beam-line absorbers for conventional NC cavities, the presence of a large beam tube in a coaxial resonant cavity does not affect the accelerating performance. This enables effective HOM damping while maintaining a high shunt impedance in a NC cavity. The numerical simulation results show that a compact copper cavity with effective HOM damping and excellent RF properties has been achieved.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P33
About •	Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MO2L3

Review of Harmonic Cavities in Fourth-generation Storage Rings

storage-ring, synchrotron, electron, survey

8

F.J. Cullinan, Å. Andersson, P. Tavares
MAX IV Laboratory, Lund University, Lund, Sweden

Several third generation light-source storage rings have used harmonic cavities to lengthen the electron bunches. With the advent of the fourth generation however, they have become an almost universal feature as the small transverse electron beam sizes make long bunches essential for increasing Touschek lifetime and reducing emittance blow-up from intrabeam scattering. Multiple technological solutions exist for the implementation of harmonic cavities and which to use remains an open question for many facilities. This is therefore a very active area of study in which there is strong collaboration within the community. Avoiding coherent collective beam instabilities is of particular concern. In this talk, I will summarise the results obtained so far. I will also give an overview of the observations made at the MAX IV 3 GeV ring, the first fourth generation storage ring which was commissioned with normal-conducting passive harmonic cavities already installed. Finally, I will discuss potential future directions.

Slides MO2L3 [3.035 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO2L3

About •

Received ※ 24 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 27 August 2023 — Issued ※ 02 December 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MO3B2

Beam Dynamics Using Superconducting Passive Harmonic Cavities with High Current per Bunch

dipole, synchrotron, impedance, emittance

14

A. Gamelin, V. Gubaidulin, A. Loulergue, P. Marchand, L.S. Nadolski, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France
N. Yamamoto
KEK, Ibaraki, Japan

In 4th generation synchrotron light sources, harmonic cavities (HCs) are critical components needed to achieve the required performance. They provide longer bunches, which helps to reduce statistical effects (intra-beam scattering and Touschek effect). In "timing" modes, where the bunch spacing is larger than in conventional modes and the number of particles per bunch is higher, this need is even greater. In this article, we present the beam dynamics in the high current per bunch regime and how it interacts with the single bunch collective effects. In particular, a dipole-quadrupole instability is observed above the microwave threshold and a coupling between the dipole and cavity modes is shown to limit bunch lengthening at low current. The effective gain from the use of HCs in terms of lifetime, emittance, and energy spread is also discussed.

Slides MO3B2 [1.529 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B2

About •

Received ※ 13 August 2023 — Revised ※ 15 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MO3B3

Bunch-lengthening RF System Using Active Normal-conducting Cavities

kicker, synchrotron, beam-loading, controls

18

N. Yamamoto, D. Naito, S. Sakanaka, T. Yamaguchi
KEK, Ibaraki, Japan
A. Gamelin, P. Marchand
SOLEIL, Gif-sur-Yvette, France

Bunch lengthening using a double RF system (fundamental + harmonic cavities) is essential in preserving the extremely low emittance in fourth and future generation synchrotron light rings. Recent studies have revealed that, in many cases, unstable beam motions, as so-called "mode-0" and "periodic transient beam loading" instabilities, prevent from reaching the optimum bunch lengthening condition with low and high beam current, respectively, even in symmetric filling patterns. While reducing the R/Q is beneficial for the latter, it will worsen the former. To achieve an efficient bunch lengthening system, we proposed a promising solution based on a powered TM020-type harmonic cavity with RF feedbacks (RF-FBs)*, as reported at FLS2018. Based on this concept, we are developing both fundamental and harmonic cavities using the TM020 resonant mode**, a kicker cavity having a bandwidth >5MHz***, bunch-phase monitor (BPhM) and RF-FBs. In this presentation, we describe our overall bunch lengthening system including cavity and BPhM designs. We also present particle tracking simulation results demonstrating that the bunch lengthening limitations can be alleviated by means of direct RF-FBs****.
* N. Yamamoto et al., PRAB 21, 012001, 2018.
** T. Yamaguchi et al., accepted in NIM A.
*** D. Naito et al, IPAC2021, MOPSB331, 2021.
**** N. Yamamoto et al., IPAC23, WEPL161, 2023.

Slides MO3B3 [2.655 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B3

About •

Received ※ 22 August 2023 — Revised ※ 23 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU1C1

An Efficient Optimisation of a Burst Mode-Operated Fabry-Perot Cavity for Compton Light Sources

laser, electron, photon, optics

46

V. Mușat, E. Granados, A. Latina
CERN, Meyrin, Switzerland
E. Cormier
CELIA, Talence, France
G. Santarelli
ILE, Palaiseau Cedex, France

The burst mode operation of a Fabry-Perot cavity (FPC) allows for the generation of a high-intensity photon beam in inverse Compton scattering (ICS) sources. The geometry and burst mode parameters of the FPC can be optimised to maximise the scattered photon flux. A novel optimisation method is presented, significantly improving processing speed and accuracy. The FPC’s dimensions, mirror requirements, and effective energy can be obtained from the electron beam parameters at the interaction point. A multi-objective optimization algorithm was used to derive the geometrical parameters of the FPC; this brought orders of magnitude increase in computation speed if compared to the nominal Monte Carlo-based approaches. The burst mode parameters of the FPC were obtained by maximizing the effective energy of the laser pulse in the FPC. The impact of optical losses and thermal lensing on the FPC parameters is addressed. Preliminary parameters of an ICS source implementing this novel optimisation are presented. The source could reach high-performance photon beams for high-energy applications.

Slides TU1C1 [1.776 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C1

About •

Received ※ 22 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU1C2

Evolution of the Inverse Compton Scattering X-ray Source of the ELSA Accelerator

laser, electron, alignment, scattering

50

A. Pires, R. Rosch, J. Touguet
CEA, Arpajon, France
N. Delerue
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
V. Le Flanchec
CEA/DAM/DIF, Arpajon, France

The Inverse Compton Scattering (ICS) X-ray source of ELSA accelerator at CEA-DAM, presents an efficient approach for generating X-rays with a compact linac. The source consists of a 30 MeV, 15 ps rms, up to 3 nC electron beam; and a table-top Nd:YAG laser. X-rays are produced in the 10-80 keV range, higher X-ray energies achieved with frequency doubling of the laser. The yield is increased by a factor of 8 thanks to an optical mirror system developed at CEA, folding the laser beam path and accumulating successive laser pulses. We present a new version of the device, with improvement of mechanical constraints management, adjunction of motorized mirrors, and a new imaging system. A Chirped Pulse Amplification (CPA) system was also designed, enabling higher amplification levels without exceeding laser damage threshold. The uniqueness of this CPA system lies in its use of a short wavelength bandwidth, ±250 pm after Self-Phase Modulation (SPM) broadening, and a line density of 1850 lines/mm for the gratings of the compressor. The pulse is stretched with a chirped fiber Bragg grating (CFBG) before amplification in Nd:YAG amplifiers, and compressed by a double pass grating compressor.

Slides TU1C2 [7.085 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C2

About •

Received ※ 25 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU3D4

Compact HOM-damped RF Cavity for a Next Generation Light Source

HOM, damping, impedance, operation

74

H. Ego
KEK, Ibaraki, Japan
T. Asaka, N. Nishimori
QST, Sendai, Miyagi, Japan
T. Inagaki, H. Tanaka
RIKEN SPring-8 Center, Hyogo, Japan
T. Ohshima, T. Tomai, H. Yamaguchi
JASRI, Hyogo, Japan

A beam-accelerating RF cavity with a new HOM-damping structure was designed in order to suppress coupled-bunch instabilities in a next generation light source with an ultra-low emittance and supplying X-rays approaching their diffraction limits. The TM020 mode at 509 MHz is selected as a beam-accelerating mode because it has a high Q-value of 60,000 and a shunt impedance sufficient for beam acceleration and brings a compact HOM-damping structure to the cavity differently from massive types of cavities with waveguides or pipes extracting HOM power. Two shallow slots are cut on the cavity inner-wall and materials absorbing RF waves are directly fitted into them. They work as HOM dampers without affecting the RF properties of the beam-accelerating mode. A prototype cavity of OFHC copper was fabricated to demonstrate the HOM-damping and generating an accelerating voltage of 900 kV in the cavity. Since the cavity was successful in operation up to 135 kW, the feasibility of both the high-power operation and the damping structure was proved. Four actual cavities were produced and installed to the new 3-GeV synchrotron radiation facility, NanoTerasu in Japan.

Slides TU3D4 [8.581 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU3D4

About •

Received ※ 22 August 2023 — Revised ※ 23 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU4P34

Recent Developments of the cSTART Project

storage-ring, injection, electron, lattice

155

M. Schwarz, A. Bernhard, E. Bründermann, D. El Khechen, B. Härer, A. Malygin, A.-S. Müller, M.J. Nasse, G. Niehues, A.I. Papash, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski, C. Widmann
KIT, Karlsruhe, Germany

The combination of a compact storage ring and a laser-plasma accelerator (LPA) can serve as the basis for future compact light sources. One challenge is the large momentum spread (~ 2%) of the electron beams delivered by the LPA. To overcome this challenge, a very large acceptance compact storage ring (VLA-cSR) was designed as part of the compact STorage ring for Accelerator Research and Technology (cSTART) project. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for the VLA-cSR to benchmark and emulate LPA-like beams. In a second stage, a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and the Helmholtz Institute Jena (HIJ). The small facility footprint, the large-momentum spread bunches with charges from 1 pC to 1 nC and lengths from few fs to few ps pose challenges for the lattice design, RF system and beam diagnostics. This contribution summarizes the latest results on these challenges.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P34

About •

Received ※ 21 August 2023 — Revised ※ 22 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WE4P33

Design of a 166.6 MHz HOM Damped Copper Cavity for the Southern Advanced Photon Source

HOM, impedance, damping, photon

207

J.Y. Zhu, X. Li, Z.J. Lu
IHEP, Beijing, People’s Republic of China
J.B. Yu
IHEP CSNS, Guangdong Province, People’s Republic of China

Funding: This work was supported by the National Natural Science Foundation of China (12205168).
The Southern Advanced Photon Source (SAPS) aims to achieve ultra-low emittances and is expected to adopt low-frequency cavities (< 200 MHz) to accommodates on-axis injection. This paper focuses on the design of a 166.6 MHz HOM-damped normal conducting (NC) cavity for the SAPS. We propose a novel approach to achieve efficient HOM damping by optimizing the lowest frequency HOM and implementing a beam-line absorber in a coaxial resonant NC cavity. Notably, unlike beam-line absorbers for conventional NC cavities, the presence of a large beam tube in a coaxial resonant cavity does not affect the accelerating performance. This enables effective HOM damping while maintaining a high shunt impedance in a NC cavity. The numerical simulation results show that a compact copper cavity with effective HOM damping and excellent RF properties has been achieved.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P33

About •

Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)